This invention relates to a tack button, and more specifically to a structure for securely fixing in place a backing core fitted within the button body of a tack button.
Generally, tack buttons comprise a button body and a backing tack piece. The button body, in turn, is made up of a front member constituting the face of the button, a back member with means for receiving and locking the shank of the tack piece, and a backing core to deform the protruding end of the tack piece shaft on clinching. For the fabrication of the button body, the backing core is fitted into a space formed between the front and back members so as to receive the protruding end of the tack piece. The core is then fixed in place between the two members crimped together at the edges. If the crimping force applied is insufficient, a slight gap may be left between the backing core and the front member or the back member. The gap can cause the core to slide or shake inside the button body when the button is subjected to some external force. When this happens, the core hits against the front or back member or both to clink.
If the crimping force is increased sufficiently to preclude this possibility, the backing core is pressed so strongly against the front member that the latter will be marked by the contour of the underlying core, with a consequent reduction in its marketable value. Increasing the crimping force in this manner is impracticable for buttons with embossed patterns on the surface. In view of these, it has been necessary to adjust the applicable crimping force delicately by types of buttons, with difficulties involved in attaining proper crimping individually.
For enhanced strength or rigidity of the back member, some existing tack buttons use a back member formed with a circular reinforcing groove protruding at the bottom on the side in contact with the backing core. The reinforcing groove is rigid enough to remain practically undeformed elastically by weak crimping forces. In order that the backing core be fixed securely within the button body it is essential to increase the crimping force to press the reinforcing groove against the backing core to effect the elastic deformation of the groove. The application of the increased force, however, leads to the unwanted marking of the front member with the underlying core, as noted already.